Screening of Diseases: Is it Really Necessary? Why?

Table of Contents

What is Screening?

Screening is well-defined as the reasonable identification of unrecognized illness/disease in an apparently healthy, asymptomatic individual by means of tests, experiments, inspections or other trials that can be applied rapidly and easily to the target population
Screening test is used to identify people who require further investigation to determine the presence or absence of disease
It can be also defined as the search for unrecognized disease in apparently healthy persons or individuals.
Screening is not primarily a diagnostic test.
Screening is a procedure – one that activates with a summons to take part and ends with a cure for applicably known entities.
It screens out apparently healthy individuals who probably have a disease from those who probably do not.
Individuals with suspicious findings must be referred to the physician for diagnosis and necessary treatment.
The process of screening begins with inviting individuals to participate in the screening process and ends with providing appropriate treatment to appropriately identified individuals.

Screening differs from periodic health examination on the following basis:

To identify early evidence of an abnormality or abnormalities in an individual
To recommend preventive strategies and treatment to an individual for better health outcomes

The disease to be screened should fulfill the following criteria before it is considered for screening. They are:

The condition should be an important public health problem in terms of its frequency and severity.
There should be a recognizable latent or early symptomatic stage
The natural history of the condition/disease should be adequately understood
There should be a recognizable latent or asymptomatic stage
There should be an accepted treatment for patients with recognized disease
There should be a suitable test or examination that has a high level of accuracy
There should be a test that can identify the disease prior to the onset of sign and symptoms. Moreover, the test should be
- acceptable to the population
- reasonably inexpensive
- safe
- able to discriminate between disease and non-disease population
There should be an agreed policy on whom to treat as patients. E.g.: borderline of diabetes
Facilities for diagnosis and treatment should be available.
There should be good evidence that early detection and treatment reduces the morbidity and mortality from disease.
The cost of screening (including diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole, and
Screening should be a continuing process and not a ‘once and for all’ project.
The expected benefits (e.g. number of life saved) of early detection exceeds the risk and cost.

According to World Health Organization (WHO), effective screening program must meet the following criteria:

Mechanisms for systematic invitation and follow-up for individuals identified by the screening test as having an abnormal finding (call and recall mechanisms);
Participation of over 70% of the target population to be screened;
Necessary infrastructure and resources to offer the test periodically and to adequately diagnose and treat those found to have cancer or a precancerous lesion, and;
Robust monitoring and evaluation framework to assure quality.

Every single screening test can be risky as well. For instance, x-ray investigations uncover the body to radioactive particles, and endoscopy of the bowel can result in blood loss or (in rare cases) severe damages.
Therefore, it is essential that both the welfare and problems of a screening test should be evaluated in studies before presenting it at an enormous scale. That way, investigators can discover whether the aids of the screening test be greater than the hazards.

This is a term used to specify the extensive screening of entire population sets.
It used it to denote to the screening wherever there is no selection of population sets is prepared.

This term is used for the screening of chosen high-risk groups in the population.
It may perhaps still be large-scale, and be able to consider as one and only form of population screening.

It has been well defined as the practice of dual or additional screening tests in the mixture to large clusters of individuals.

A new kind of screening is known as opportunistic screening: this is where somebody visits a doctor for a specific cause and, whereas they are offered a supplementary test, for example, blood pressure measurement.

1. Lead-time:

Lead-time is the recess among the time of disease finding through screening and the time of disease recognition in the deficit of screening.
The lead-time formed by a screening program for a certain individual be influenced by the time of screening, in respect to the pre-clinical phase, and on the sensitivity purpose of the screening test.

2. The Detectable Pre-Clinical Phase:

The time interval between potential detection by screening and far ahead recognition after symptoms is the “detectable pre-clinical phase” or DPCP.
Deprived of screening, diagnosis of disease only take place after signs progress.
Nonetheless, illness often activates long before symptoms take place, and even in the absenteeism of symptoms, there might be a point at which the disease could be identified by a screening test.

Screening tests are safe and relatively cheaper compared to the general test or examination.
It helps to identify diseases at an initial phase before any symptoms become visible.
The medical tests used for screening resolutions are regularly not suitable for making a concluding analysis. As a substitute, several tests are used to identify any oddities first, which are then viewed at more thoroughly in further assessments.
It is always beneficial for early diagnosis and treatment of disease.

Screening of certain diseases like cervical screening will not inhibit all circumstances of cervical cancer.
In some diseases like cervical cancer, certain women will still progress cervical cancer in spite of consistent screening.
Certain abnormal cell fluctuations might be neglected.
Screening will not discover each anomalous cell alteration
Screening test can sometimes be detrimental as well, if enough precautionary measures are not taken.
It is less accurate.
Screening is not the base for treatment.
Screening program can only be measured a “preventive” measure if it targets to define and affect threats.